Battery Maintenance

Keep your battery in peak condition

Many times overlooked when it comes to servicing, it takes little to keep your battery in good condition and extend it's life but can save a lot of trouble later. Especially on those very cold mornings when your car won't start!

Check the condition of the terminals

Poor connections due to loose clamps or corrosion can create starting and charging problems.

The battery has two terminals (+ and -). Most vehicles use a negative earthed system. This means that the bodywork, engine and other metal parts are negative (earth) also.
If you were to disconnect the positive terminal first with a metal tool, that tool could come into contact with any metal part of the body/engine and create a short and result in a spark. For this reason whenever you disconnect battery terminals always remove the negative terminal first. When re-connecting, connect the postive first.

Once removed check the connector clamps and battery posts for any corrosion (normally like a white powder). Using a wire brush and/or some fine sandpaper clean the inside and outside of the connector clamps and also around the battery terminals. You can, if you wish, use a baking soda solution to clean the corroded parts more thoroughly.

Reconnect the connector clamps making sure they are adequately tight but do NOT overtighten. Then cover both terminals with a layer of petroleum jelly or equivalent grease.

Check your electrolyte levels

The electrolyte is the acid (sulphuric) and water solution used in a car battery. Over time water can evaporate (faster in hotter climates) and this needs to be topped up before damage occurs to the battery. Many batteries today are sealed for life and do not have access to be topped up. If they are accessible there will be either one or two plastic strips which prise up or individual large round plastic screw heads. Once the caps are removed look to see whether the electrolyte is above the metal plates. If any part of the metal plate is above the electrolyte level then you need to top up.

Use distilled water to top up (not tap water, unless it's for emergency usage on an already poor battery) and only top up so the metal plates are just covered by a few mm or you will weaken the electrolyte.

Some batteries have indicator windows to quickly advise whether the electrolyte level is low and also to advise the state of the battery. Many sealed for life (maintenance free) batteries will have a window to advise condition and they cannot be topped up. They normally contain more advanced technology to prevent water loss.

The average life of a lead acid car battery is normally 4 to 5 years. They may go on working for much longer but at near freezing temperatures turning the engine over will be hard.

Check the condition of the battery

A simple way to check your battery is with a voltmeter. You can buy these now for just a few pounds. By connecting the + and - probes of the meter to the battery check the voltages as follows (battery disconnected):

10.45 to 10.65 volts - Battery has a shorted cell and must be replaced.

11.89 volts - Zero charge

12.24 volts - 50% charge

12.65+ volts - 100% charge

Note: If the battery has just been charged you must eliminate surface charge first. You can do this by allowing the battery to sit for 12 hours or turn the headlights on for 5 minutes with the engine off. With surface charge you will get misleading higher volt readings.

Check the alternator is working

Another reason why your battery may be discharging is down to problems in the charging circuit. This is normally denoted by a warning light appearing on the dash (battery symbol) but sometimes it is very dim or fluctuates. Check the alternator is charging properly by starting the engine and then checking the voltage. The voltage will normally read between 14 and 14.5 volts if the alternator is charging properly. It can range between 13 and 15 volts depending on the load and temperature - higher when it is cold or when there is a greater load on the battery.

If the alternator appears not to be charging properly, check the alternator belt is tight before suspecting a fault in the alternator.

Precautions

You should always take serious precautions with batteries.

Lead acid batteries are filled with a sulphuric acid solution which is highly corrosive. During charging they can emit flammable gases so do not smoke or have naked flames around them.

Any tests on electrolyte should be done with protective eyewear and gloves.